Teleprinter arrangement for reducing received signal distortion



y 5, 1970 D. SCHENK ETAL 3,510,582

I TELEPRINTER ARRANGEMENT FO R REDUCING RECEIVED SIGNAL DISTORTIQN Filed Dec. 20, 1965 2 Sheets-Sheet 1 Fig. I

- INVENTORS OIETER SCH'A/K HORST GAL/PP- May 5, 1970 D. scHENK ETAL 3,510,582

TELEPRINTER ARRANGE ENT FOR REDUCING RECEIVED SIGNAL DIS'I'ORTION Filed Dec. 20. 1966 E 2 Sheets-Sheet 2 Fig. 2

INVENTORS D/ETER SC HNK HORST GAUPF' ATTORNEY United States Patent 3,510,582 TELEPRINTER ARRANGEMENT FOR REDUCING RECEIVED SIGNAL DISTORTION Dieter Schenk, Pforzlieim, and Horst Gaupp, Enzberg, Germany, assignors to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Dec. 20, 1966, Ser. No. 603,213 Claims priority, application Germany, Dec. 23, 1965, St 24,800 Int. Cl. H041 17/16 US. Cl. 178-175 3 Claims ABSTRACT OF THE DISCLOSURE An arrangement for reducing the effects of received signal distortion in teleprinters of the type which operate on the start-stop code principle. The disclosure defines an addition to the mechanical storage facilities therein to prevent falsification of code elements resulting from distorted start-stop pulses. There is provided a component part coupled to the first storage element which permits an intermediate storage of the desired first element marking until the storage element is ready to accept it.

The present invention relates to an arrangement for reducing received signal distortions in printing telegraph apparatus operating on the start-stop principle. For the purpose of storing the code combinations arriving in series, there are used storage elements which, prior to a new storing, must have reassumed a predetermined, spring-loaded starting position.

In receiving systems of the type described above, it is necessary that both the scanning and the resetting of the storage elements to their starting positions be effected within a period of time determined by the stop and start element of two successively following signals.

As the transmitting speed increases, this time becomes so short that, in view of acceptable mass acceleration relationships, almost the entire time which is theoretically available, must be utilized. However, period of time may vary considerably as a result of different transmitting and receiving conditions, for example, the reception of a stop pulse which has been shortened by distortion. The thus extended or earlier arriving start element of the subsequently following signal will effect a corresponding premature tripping of the selector cam sleeve. The tripping of the marking of the storage element associated with the first signal element is effected thereby at a time position in which this element, at the scanning time position, has not yet been released again by the reset mechanism, and is therefore incapable of complying with the marking request. Consequently, there will result a signal which is falsified in its first signal element.

In order that this disadvantage be avoided, the present invention proposes to assign to the storage element which is associated with the first signal element, a latching pawl which, in the case of a premature selection of the storage element, retains the storage marking in excess of the tripping time position. In accordance with the invention the storage function of the latching pawl is eliminated after the storage element has reliably assumed a position corresponding to the storage marking.

The invention will now be explained in detail with reference to the accompanying drawings, in which:

FIG. 1 schematically illustrates a receiving system of a conventional type in its normal condition, and provided with the arrangement according to the invention; and

FIG. 2 shows the receiving system according to FIG. 1 at the time position in which, due to a premature tripp CC ping of the selector cam sleeve, there is effected an intermediate storage of the premature tripping pulse.

The receiving system as schematically shown in FIGS. 1 and 2 is an arrangement of the type known per se, in which the position of the armature 2 of a not shown receiving magnet is being scanned successively in the manner known per se by a number of sensing levers 3 corresponding to the respectively employed unit code. Illustrated is the portion of the apparatus associated with the first signal code element. The sensing lever 3, which is being acted upon by the spring 3a, is released to perform a swivel motion in the clockwise direction within the recess 10 of the associated control disc 1 forming part of the selector cam sleeve. The position of the armature 2 determines whether the momentarily released sensing lever 3 is actually capable of engaging (armature position FIG. 2), or not (armature position FIG. 1). Regarding FIG. 2, the clockwise swivel motion of sensing lever 3 results in a counterclockwise rotation of ratchet pawl 4 which, as shown FIG. 1, is initially in engagement with a storage element 5. The thus released storage element 5, under the action of the spring 5a, moves into the storage position limited by a limit stop pin 6, characterising the received condition of the associated code element. In order to effect a new storing, the storage elements 5, subsequent to the effected evaluation of the stored combination, are reset to the normal position as shown in FIG. 1 by the reset bolt 8a of a reset device 8 controlled via a cam plate 9. This resetting and the subsequent release of the storage elements 5 by the bolt 8a must be carried out such that the element conditions of the following signal can be stored without error into the storage device composed of the elements 5.

In the case of machines with a high signal frequency, however, this requirement is difficult to fulfill, as on one hand, the reset time for the storage elements cannot be reduced at will due to the appearing mass forces and on the other hand, time displacements arise which are due to pulse distortions. These may cause a premature starting of the selector cam sleeve causing an overlap between the resetting of the storage elements and the reception of the first signal element. Since the scanning or sensing. time, due to the narrow recess 1a, is very short, it may happen that the lifted ratchet pawl 4 will have reassumed its previous position before the storage element 5 has been able to react accordingly. The storage element 5, prevented from being released, will therefore effect the printing of a faulty character during the evaluation.

For avoiding this disadvantageous effect, a latching pawl 7, pivotably mounted to a stationarily arranged bolt 7b, is assigned, in accordance with the invention, to the storage element 5 associated with the first signal element. This latching pawl 7 under normal receiving conditions, assumes the position as shown in FIG. 1 under the influence of the reset bolt 8a in opposition to the action of the spring 7c. Latching pawl 7, therefore, remains ineffetive under normal receiving conditions.

However, if the case arises, as shown in FIG. 2, for example a reduced stop element, the selector cam sleeve is prematurely released by the start element of a subsequently following signal in such a way that the scanning or sensing time position, in accordance with the representation, will fall within the period of time intended for the resetting of the storage elements. Thus the latching pawl 7 as released by the reset bolt 8a, and unthe action of its spring 70, will assume the position as shown, in which the actuator of the latching pawl 7a will engage the pawl actuator 4a of the momentarily lifted ratchet pawl 4. This retains the latter until, due to the rearward movement of the resetting device 8, the latching pawl 7, in accordance with FIG. 1, is brought out of engagement with the ratchet pawl 4. Under the action of the spring 4b, ratchet pawl 4 will now jump into the locking position. However, since the associated storage element 5, under the action of the spring 5a, has followed the reset bolt 8a to the limit stop 6, it has already assumed a position at the time of release of the ratchet pawl 4. Thus an erroneous blocking of the associated storage element 5 in the normal position is reliably avoided with respect to the time of the currenting sensing cycle.

Between the storing of the first and tht second elements of a received code combination there to be received, there exists at least a time interval of 10 ms. (100 baud-operation). This is sufficient to prevent falsification of the subsequently following signal elements which might be due to the aforementioned causes. Up to this time position the remaining storage elements 5 are in any case released by the reset device 8, so that in accordance with the present invention, merely the storage element 5 which is associated with the first signal element, will have to be provided with a latching pawl 7. By this simple measure it is made possible, with respect to receiving systems of the aforementioned kind, to avoid a considerable amount of receiving errors which have hitherto been caused by signal distortions and/or machinebound time displacements.

What is claimed is:

1. An improved teleprinter arrangement for reducing received signal distortions in printers operating on the start-stop principle, in which mechanical storage elements are used for storing code combinations arriving in series, and in which the mechanical storage elements, prior to a new storage, are returned to a predetermined normal position, wherein the improvement comprises a latching pawl (7), pivotably coupled to a storage element (5) associated with the first signal element by a bolt (7b) afiixed thereto to permit, in the case of a premature selection of the storage element (5), intermediate storage of the code marking condition in excess of the tripping time, with the storage function of said latching pawl (7) being eliminated after the storage element (5) has assumed a position corresponding to the code marking condition.

2. An arrangement according to claim 1 wherein said latching pawl (7 has a latch actuator extension (7a) by which said latching pawl (7) latches a ratchet pawl (4) associated with the storage element (5) for a period in excess of the time of premature sensing so as to provide proper storing of the received code element by the storage element (5).

3. An arrangement according to claim 2 wherein said latching pawl (7) has an arm portion which is positioned to intercept the reset bolt (8a) of the reset device References Cited UNITED STATES PATENTS 2,623,118 12/1952 Salmon 178-175 2,667,628 1/1954 Chaveneaud 178-175 3,440,344 4/1969 Smessaert 17817.5

THOMAS A. ROBINSON, Primary Examiner U.S. Cl. X.R. 

